In order to provide a speech input system for having access from a mobile terminal to a network through speech, and receiving a service from a provider for providing information, the speech input system comprises speech input/output mean, and an access status display mean, a speech portal server (50) provided with a speech recognizing mean to recognize it as a text, a command converting mean for checking the recognized text with a command text dictionary, and separating it into a command text and an object text, and a conversation control mean for having an access to, and receiving a service from a provider which provides different information based on the separated texts, and providing the speech input terminal with the service, and a provider (60) for searching information based on the command text and the object text received from the speech portal server, and serves the speech portal server with a search result.